EFFECTIVE-MASS OF A CHARGED-PARTICLE TRAVELING ABOVE DIELECTRIC FLUIDSURFACE

The behaviour of a charged particle travelling above the surface of a dielectric fluid at constant velocity Vis considered. The fluid is tak en to be incompressible, inviscid and infinitely deep, and the particl e velocity is assumed to be smaller than the minimum phase speed of ca pillary gravity waves, c(min). Because of the electrostatic coupling b etween the charged particle and the fluid, the particle should induce a bump on the surface. We find that the bump volume Omega is independe nt of the velocity V of the particle. For V much less than c(min), the fluid momentum Q varies linearly with the particle velocity. For larg er values of V, however, Q deviates from linearity and diverges like [ 1 - (V/c(min))](-1) as Tr approaches c(min). From the calculation of Q , we derive the induced mass of the particle, which is not directly re lated to the bump volume.